Quarter adders



y 17, 1960 T. H. BONN ETAL 2,937,286

QUARTER ADDERS Filed April 7. 1955 FIG. I.

npuL'L 5 Input 8 FIG. 2.

Input A Input B Output Tl T2 T3 IN V EN TORS THEODORE H. BONN BY Jvmvmmasmrm AGENT 2,937,286 l s t d May i 7 2,937,286 QUARTER ADDERS.

Theodore H. Bonn and John Presper Eckert, Jr. Phila- 'delpliia, Pa.,assignors to Sperry Rand Corporation, a corporation of DelawareApplication April 7, 1955, Serial No. 499,808 16 Claims. (Ci. 307-88)Input A Input B As will be seen from an examination of the foregoingtable, the presence. of one or the other, but not both, of two inputsignals effects an output signal, while the simultaneous presence orabsence of the said two input signals results in there being no outputsignal. Units capable of performing quarter addition in accordance withthe preceding truth table form a basic portion of more complexcomputation devices.

In the past, quarter adders have utilized vacuum tube circuitry for themost part, and have accordingly been subject to the disadvantages thatthey are relatively fragile in construction and subject to operatingfailures. The present invention serves to obviate the foregoingdisadvantages and, ineso doing, provides a quarter adder structureutilizing a pulse transformer as the basic portion thereof.

It is accordingly an object of the present invention to provide improvedquarter adders foruse in computing applications. r

A further object of the present invention resides in the provision of animproved quarter adder device which is inore rugged in construction andless subject to operating failures than has been the case heretofore.

Still another object of the present invention resides in the provisionof a quarter adder device employing a pulse transformer as the basiccomponent thereof.

Ast-ill further object of the present invention resides in the provisionof improved devices for penforming quarter addition, which devices areselectively responsive to the simultaneity, or lack thereof, of twoinput signals to produce a characteristic output.

As has been mentioned previously, the present invention, in effectingthe foregoing objects, utilizes a pulse transformer, and two signals,which have been termed flnput A and Input B in the truth table givenpreviously, are coupled respectively tothe primary side of {the saidtransformer. In practice, the said primary side of the transformer maycomprise a single primary winddug, in which case the twoinput pulses maybe selectively ctiupledto opposite ends thereof. However, it should benOted-that the said primary side may further comm p wssii i- 9 4 9 wi itp o i ola tie r rss v y sad. the so W9 in u signals m be p tivelycoupled to t ese two windings. should be understood therefore that inthe following discussion, this latter configuration maybe substitutedfor the single primary winding shown, without ailhecting the operationof the device substantially.

By utilizing the transformer construction mentioned above, the presenceof one only of the said two inputs will effect a current flow throughthe transformer primary windingQor windings, and this current flow willn t r in u e volt e i he t ans rm e ary- I-Iowever, if both inputsshould be applied to the primary side of the transformer simultaneously,they effectively it 9%? ass uh by n volta e is n u d in e ansf r sssndav and n ou m be ke er r m ins- 9nd th e re t pu s rmer s n sur Q? he Preen i t n rates in strict conformity with the truth table givenpreviously.

h fo o n swe s advan a es cons n and operation of the present inyentionwill be more readily seen rqm tbs-fisheries QQSFI P Q n accompanyingdrawings, which:

Figure 1 is a schematic diagram of one form of quarter adder inaccordance with the present invention;

Figure 2 is a simplified waveform diagram illustrative of the operationof the device shown in Figure l, as well o h d i shown in E 3 an Figure3 is a soheniatic diagram of a modified form o q r add esswdsnes ith h Pe v io Referring now to Figure 1, it will be seen that, in acso slss swith 9 sun o t e P es n invention, a pulse F ?!v in?! I may e u ilize han a Single p y Windi .19 and WP eco ar w n n s -11 and 1 whi h e nda y wndin s a e ou i o t i y to one another. Again, it should he noted, ofcourse, that th Pr m W ndin Q 1 J1 s u d in a mpr s two windings oun dat opposite polarity to one another, in which case the P1 13? input vt0be described may be coupled to one end respeetively of each of the saidpri mary windings, the other ends of the said primary .windings beingreturned to ground; In the specific example chosen, one end of theprimary winding 10 is coupled to a terminal 13 ,connected in turn to asource of selectively applied pulses, :lrereinafter termed Input A; theother 3nd of the said primary winding ll) is further coupled to aterminal 1fl which is connected to a further source of selectivelyapplied input pulses, hereinafter termed Input B. Secondary windings 11and 12 are each connected via -recti lier s D1 and D2, respectively,across a load impedance R and theoutput of the device is taken at atrrnina'l l5 eonneeted to one end ,of the said load impedance RReferring .to Figure 2, the op i of the quarter adder shown in Figure ;1will become readily apparent. If we should assume that during a timeinterval t1, a positive-going Input A pulse is coupled to the primary 10via terminal ,13, there being no further pulse applied to terminal 14, acurrent will flow through the said primary winding 10, inducing voltagesin the secondaries 11 negative on the anode of rectifier D1 andpositiveon the anode of rectifier D2. Current will therefore now fiow' throughthe secondary winding 12 and impedance R via rectifier D2; and again anoutput pulse will appear at the terminal 15. If, however, during a timeinterval t3, input pulses should be applied toboth terminals 13 and 14,the simultaneous voltages so applied to opposite ends of the primarywinding will etfectively nullify one another and no current will flowthrough the said primary winding 10 whereby no output appears acrossload impedance R Thus, an output pulse is obtained at output terminalonly when a single input is present at either terminal 13 or terminal 14on the primary side.

and 14, or no inputs at either terminal 13 or terminal '14, will resultin there being no output-pulse at terminal 15. The system thus acts as aquarter adder, in compliance with the truth table given previously. 7

It should be noted that by the arrangement shown, the polarity of outputpulse appearing a't'terminal 15 is the same whether the input causingthe, said output pulse is applied at terminal 13 or terminal 14. Itshould further be noted that inasmuch as current flow-through theprimary winding 10, due to the application of a single input pulse only,utilizes the other non-pulsed input terminal as the return paththerefor, the'signal sources coupled to the terminals 13 and 14 shouldbe low impedance sources, and in this respect a low impedance source isdefined 'as one capable of receiving a reverse current flow at itsoutput terminals.

If it is not desired to use'the pulse transformer configuration and/orsignal sources of Figure 1, anarrangement such as has been shown inFigure 3 may be employed. This modified arrangement utilizes but asingle secondary winding and, in addition, may employ high impedancesignal sources, in contradistinction to Figure 1, inasmuch as, due tothe provision of auxiliary current paths, the signal sources need notaccept reverse current flow at their output terminals. The quarter addershown in Figure 3 again comprises a pulse transformer T3 having aprimary winding 30, and a single secondary wind ing 31. The upper end ofprimary winding 30 is coupled via a rectifier D6 to an input terminal 32selectively energized from a source of Input A pulses and the lower endof primary winding 30 is further coupled via a rectifier D7 to an inputterminal 33, to which is coupled a further source of selectively appliedInput B pulses. The upper end of primary winding 30 is coupled viaarectifier D8 to ground and is further coupledviaa resistor R2 to asource of negative potential V. Similarly, the lower end of primarywinding 30 is coupled via a further rectifier D9 to ground and via afurther resistor R3 to the source of negative potential V. The outputpotentials appearing across secondary 31 of the pulse transformer T3 areapplied to a conventional bridge rectifier 34, the operation of which iswellknown, and the output of the said bridge rectifier is taken across aload resistor R at an output terminal 35.

In the absence of input pulses at either terminal 32 or 33, a firstcurrent flows from ground via rectifier D8, through resistor R2 to thesource of negative potential V, and a further current flows from groundvia rectifier D9 through resistor R3 to the said source of negativepotential V. Thus, in-the absence of input pulses at either inputterminal, both the upper and lower ends of primary winding 30 areclamped to ground and no output can appear at the terminal 35. If now apositive-going Input A pulse should be applied to terminal 32, thisapplied pulse raises the upper end of primary winding 30 from ground anda current flows via rectifier D6, primary winding 30 and resistor R3 tosource V. Thus, the application of a single input pulse at the terminal32 will effect a positive output pulse at output terminal 35. Similarly,if an Input B pulse should be applied to the terminal 33 at a time whenthereis nojnput pulse at Simul- 'taneous application of pulses to boththe terminals 13 be raised above ground potential and a current willthen flow from the said terminal 33 via rectifier D7, primary winding 30and resistor R2 to source V. Once more, therefore, a positive-goingoutput pulse will appear at output terminal 35. If, however, thereshould be a simultaneous application of positive-going Input A and InputB pulses at each of terminals 32 and 33, both the upper and lower endsof the primary winding 30 will be raised to a like potential aboveground and no current will flow through the said primary winding wherebythere will be no output at terminal 35. Once more, therefore, the deviceacts as a quarter adder in conformity with the truth table givenpreviously.

It should be noted that the arrangements shown in Figures 1 and 3, maybe interchanged as to portions thereof, in dependence upon theparticular requirement of the signal input sources, as well as upon thepulse transformer configuration which is to be employed. Thus, either ofthe primary winding configurations shown in Figures 1 and 3 may beoperatively associated with either of the secondarywindingconfigurations shown in those figures, and the operation of the deviceso formed will be substantially as described in the previous discussion.

Thus, while we have described several embodiments of the presentinvention, it must be understood that the foregoing description is meantto be illustrative only and is not limitative of our invention. Manyvariations will be suggested to those skilled in the art, and suchvariations, which are in accord with the principles discussedpreviously, are meant to fall within the scope of the present invention,as set forth in the appended claims.

Having thus described our invention, we claim:

1. A quarter adder comprising a transformer having a 'core of magneticmaterial, primary winding means and secondary winding means carried bysaid core and inductively coupled to one another, a first pulse-typesignal source coupled to said primary winding means, a second pulse-typesignal source coupled to said primary winding means, said first andsecond signal sources being coupled respectively to opposite ends of acommon primary winding, said first source being selectively operative toeffect a first current flow in said primary winding means whereby saidfirst current fiow induces potentials of a first predetermined polarityin said secondary winding means, said second source being selectivelyoperative to effect a second current flow in said primary winding meanswhere by said second current flow induces potentials of a secondpredetermined polarity in said secondary winding means,

said first and second signal sources producing signals of like polarity,said first and second pulse-type signal sources being so coupled to saidprimary winding means that the simultaneous application of pulse signalsto said primary winding means from each of said signal sources willproduce no resultant current flow in said primary winding means and noresultant flux change in said core and secondary winding means, andmeans coupled to said secondary winding means and responsive to aresultant potential induced therein due to flow of one or the other ofsaid first and second currents for producing an output signal.

core of magnetic material, a primary winding means and secondary windingmeans carried by said core and inductively 'cdupled to one another, a'first panama signal source coupled to said primary winding means, saidfirst source being selectively operative to eflFect a first current flowin said primary winding means whereby said first current flow inducespotentials of a first predetermined polarity in said secondary windingmeans, a second pulsetype signal source coupled to. said primary windingmeans, said second source being selectively operative to eifect a secondcurrent flow in said primary winding means whereby said secondcurrcntflow induces potentials of a second predetermined polarity insaid secondary winding means, said first and second pulseatype signalsources being so coupled to said primary winding means that thesimultaneous application of pulse signals to said primary winding' meansfrom each of said signal sources will produce no resultant current flowin said primary winding means and no resultant flux change in said coreand secondary winding means, and means comprising a full wave rectifiercoupled to said secondary winding means and responsive to a resultantpotential induced therein due to flow of one or the other of said'firstand second currents for producing an output signal whose polarity isindependent.

of the polarity of potential induced in said secondary winding means.

5. A quarter adder comprising a transformer having a core of magneticmaterial, primary winding means and secondary winding means carried bysaid core and inductively coupled to one another, a first pulse-typesignal source coupled to said primary winding means, said first sourcebeing selectively operative to effect a first current flow in saidprimary winding means whereby said first current flow'induces potentialsof a first predetermined polarity in said secondary winding means, asecond pulsetype signal source coupled to said primary winding means,said second source being selectively operative to effect a secondcurrent flow in said primary winding means whereby said second currentflow induces potentials of a second predetermined polarity in saidsecondary winding means, said first and second pulse-type signal sourcesbeing so coupled to said primary winding means that the simultaneousapplication of pulse signals to said primary winding means from each ofsaid signal sources will produce no resultant current fiowin saidprimary winding means and no resultant flux change in said core andsecondary winding means, and means coupled to said secondary windingmeans and responsive to a resultant potential induced therein due toflow of one or the other a of said first and second currents forproducing an output signal, wherein said secondary Winding meanscomprises two secondary coils wound at opposite polarity to one another,means coupling one end of each of said second ary coils to one end of aload impedance, and first and second rectifier means respectivelycoupling each of the other ends of said secondary coils to the other endof said load impedance.

6. The combination of claim 5 wherein said first and second rectifiersare so poled with respect to their correspending secondary coils thatwhen one of said rectifiers is conductive the other of said rectifiersis non-conductive.

7. A quarter adder comprising a pulse transformer having a single coreof magnetic material, and first and second coils inductively coupled toone another and wound on said single core, first and second independentelectrical signal sources coupled to opposite ends of said first coil,said signal sources including means producing signals of substantiallylike potential and energy level, the application of a signal from oneonly of said signal sources causing a flux change through said coil andcore and the simultaneous presence or absence of signals from both ofsaid sources causing no resultantfiux changein said coil and core,whereby the application of an electrical signal from one only of saidfirst and second signal sources effects a flux change directly inducinga potential in said second coil, and means coupled to said second coiland responsive to' potentials induced in said second coil for producingan output signal.

8 The. combination of claim 7 including clamp means coupled to saidfirst coil, said clamp means providing a return path. for currentflowing through said first coil due to the application of a signalfromone only of said signal sources. I

9. The combination of claim 8 wherein said clamp means comprises a pairof diodes coupled respectively between opposite ends of said first coiland a point of substantially ground potential.

It). A control circuit comprising first and second coils inductivelycoupled to one another, first and second independent electrical signalsources coupled to spaced points on said first coil whereby thesimultaneous presence or absence of signals from said first and secondsources causes said spaced points to assume substantially likepotentials, and the presenceof a signal from one only of said signalsources causes said spaced points to assume diflfering potentials,whereby a current flows in said first coil between said spaced pointsonly in response to occurrence of a signal from one only of said firstand second signal sources, clamp means coupled to said first coil formaintaining said spaced points at a predetermined potential level in theabsence of signals from said signal sources, and output means coupled tosaid second coil and responsive to potentials induced in said secondcoil due to current flow between said spaced points on said first coil,whereby occurrence of a signal from one only of said first and secondsources induces a potential in said second coil thereby to directlyproduce an output signal at said output means and simultaneous presenceor absence of signals from both said first and second sources producesno current flow in said first coil and no induced potential in saidsecond coil.

11. A circuit comprising a pulse transformer having a primary windingand a secondary winding, means for coupling a first high impedancepulse-type signal source to one end of said primary winding, means forcoupling a second high impedance pulse-type signal source to the otherend of said primary winding, a first and a second unidirectional currentelement, means coupling said unidirectional elements from said ends,respectively, of said primary winding to a point of reference potential,a first and a second resistive element, means coupling said resistiveelements from said ends, respectively, of said primary winding to apotential source, and an output circuit coupled to said secondarywinding.

12. A device comprising a first clamping circuit and a second clampingcircuit, each of said circuits coupled to a fixed reference potentialand to a potential source having a certain polarity with respect to saidfixed reference potential, a transformer having a primary winding and asecondary winding, said first clamping circuit coupled to one end ofsaid primary winding and said second clamping circuit coupled to theother end of said primary winding, a first pulse-type signal sourcecoupled to said one end of said primary winding, a second pulse-typesignal source coupled to said other end of primary winding, each of saidsignal sources having a polarity opposite to said certain polarity, andan output circuit coupled to said secondary winding.

13. The combination as claimed in claim 12 wherein said output circuitincludes rectifying means.

14. A device including first means for receiving a first pulse-typesignal having a first polarity with respect to a reference potential,second means for receiving a second pulse-type signal having said firstpolarity, a pulse transformer having a primary winding and a secondarywinding, one end of said primary winding being coupled to said firstmeans, the other end of said primary winding being coupled to saidsecond means, a first and a second biasing means coupling said first endand said second end, respectively, to a voltage source having a polarityopposite to said first polarity, and including separate rectifier meanscoupling said ends, respectively, -to said reference potential, and anoutput circuit coupled to said secondary winding.

15. A device comprising a pulse transformer having a primary winding anda secondary winding, a first. circuit coupled to one end of said primarywinding for providinga return circuitnat said one end to a point ofreference potentialin the absence of a first signal of a predeterminedpolarity applied thereto, a second circuit coupled to the other end ofsaid primary winding for providing a return circuit at said other end tosaid point of reference potential in the absence of a second signal ofsaid predetermined polarity applied thereto, and an output circuitcoupled to said secondary winding.v V r ,16. The device as claimed inclaim 15 wherein each References Cited in the file of this patent UNITEDSTATES PATENTS 2,408,524 Mestas Oct. 1, 1946 2,445,455 Rights et al.July 20, 1948 2,640,971 MacGcorge June 2, 1953 v2,695,993 Haynes Nov.30, 1954 2,715,722 Relis Aug. 16, 1955 2,854,586 Eckcrt Q Sept. 30, 1958

